<p> Detailed Neodymium isotopic mapping was performed on grey
gneisses from the Algonquin Park area of Ontario, in the Central
Gneiss Belt of the southwestern Grenville Province. The Neodymium
model ages determined were based upon the Depleted Mantle Model of
DePaolo ( 1981c ) . The use of this model is supported by Lead-Lead
dating of zircons obtained from an orthogneissic sample. </p> <p> The wide range of model ages found ( 1.5 - 1.86 Ga ) is
attributed to the presence of a northwestward dipping, Andean
style, ensialic continental margin arc that was active in the Mid-Proterozoic
between 1.50 Ga and 1.65 Ga. The diapiric rise of
plutons produced by the subduction zone intruded continental margin
at least as old as 1.86 Ga as indicated by the oldest pluton in the
field area. Variable amounts of mixing occurred between these
orogenic rocks and the existing crustal rocks as illustrated by the
variable Neodymium model ages determined for grey gneisses
collected between 10 Km and 60 Km north of the Central
Metasedimentary Belt Boundary Zone. Major element analysis and
subsequent tectonic and petrographic discrimination diagrams such
as the AFM plot and the granitoid discrimination diagram of LeFort
and Debon ( 1983 ) also indicate that the rocks in the Algonquin
Park area are calc-alkaline, and are similar to the Peruvian Coastal Batholith. </p> <p> For grey gneisses analyzed within 10 Km of the Central
Metasedimentary Belt Boundary Zone, the range of ages is far more
restricted, suggesting that an island arc approximately 1.45 Ga was
transported by the subducting slab and later sutured onto the
existing continental margin. </p> / Thesis / Bachelor of Science (BSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19367 |
| Date | 04 1900 |
| Creators | Martin, Christopher |
| Contributors | Dickin, A. P., Geology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
Page generated in 0.0019 seconds